Low molecular weight, non-peptide fibrinogen receptor antagonists

Article abstract of DOI:10.1021/jm00101a017

The tetrapeptide H-Arg-Gly-Asp-Ser-OH (1) (RGDS), representing a recognition sequence of fibrinogen for its platelet receptor GP IIb-IIIa (integrin α(IIb)β₃), served as lead compound for the development of highly potent and selective fibrinogen receptor antagonists. Replacement of the N- terminal arginine by p-amidinophenylalanine or the Gly moiety by m- aminobenzoic acid led to compounds which are superior to the lead peptide with regard to activity and selectivity for GP IIb-IIIa vs the closely related vitronectin receptor α(v)β₃. By random screening [(p- amidinobenzenesulfonamido)ethyl]-p-phenoxyacetic acid derivatives have been identified as fibrinogen receptor antagonists. Further structure-activity relationship studies culminated in the preparation of N-[N-[N-(p- amidinobenzoyl)-β-alanyl]-L-α-aspartyl]-3-phenyl-L-alanine (29h, Ro 43- 5054) and [[1-[N-(p-amidinobenzoyl)-L-tyrosyl]-4-piperidinyl]oxy]acetic acid (37f, Ro 44-9883), which exhibit very high activity as platelet aggregation inhibitors (IC₅₀s 0.06 and 0.03 μM, respectively, human PRP/ADP) as well as marked selectivity for GP IIb-IIIa vs α(v)β₃. Since the activity of 37f in dogs declines according to a two-compartment model with an initial phase having a t( 1/2 ) of 8 min and a second phase with a t( 1/2 ) of 110 min, this compound is a suitable candidate for the development as iv platelet inhibitor.